<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
<h1>The Ajax 02 Page</h1>
<button onclick="doAjaxGet()">Do Ajax Get</button>
<button onclick="doAjaxPost()">Do Ajax Post</button>
<button onclick="doAjaxDelete()">Do Ajax Delete</button>
<button onclick="doAjaxUpdate()">Do Ajax Update</button>
<div id="result">


</div>
<script>
    function doAjaxGet() {
        let xhr=new XMLHttpRequest();
        xhr.onreadystatechange=function () {
            if (xhr.readyState==4){
                if (xhr.status==200){
                    document.getElementById("result").innerHTML=xhr.responseText;
                }
            }
        }
        xhr.open("GET","http://localhost:8080/doAjaxGet",true);
        xhr.send(null);

    }

    function doAjaxPost() {
        let xhr=new XMLHttpRequest();
        xhr.onreadystatechange=function () {
            if (xhr.readyState==4){
                if (xhr.status==200){
                    document.getElementById("result").innerHTML=xhr.responseText;
                }
            }
        }
        xhr.open("POST","http://localhost:8080/doAjaxPost",true);
        xhr.setRequestHeader("Content-Type","application/x-www-form-urlencoded");//post请求向服务器传递数据，需要设置请求头
        xhr.send("id=101&name=Computer&remark=Computer...");

    }

    function doAjaxDelete() {
        let xhr=new XMLHttpRequest();
        xhr.onreadystatechange=function () {
            if (xhr.readyState==4){
                if (xhr.status==200){
                    document.getElementById("result").innerHTML=xhr.responseText;
                }
            }
        }
        xhr.open("DELETE","http://localhost:8080/doAjaxDelete?id=101",true);
        xhr.send(null);
    }

    function doAjaxUpdate() {
        let xhr=new XMLHttpRequest();
        xhr.onreadystatechange=function () {
            if (xhr.readyState==4){
                if (xhr.status==200){
                    document.getElementById("result").innerHTML=xhr.responseText;
                }
            }
        }
        /*xhr.open("PUT","http://localhost:8080/doAjaxUpdate",true);
        xhr.setRequestHeader("Content-Type","application/x-www-form-urlencoded");//post请求向服务器传递数据，需要设置请求头
        xhr.send("id=101&name=书籍&remark=素冠荷鼎");*/
        xhr.open("PUT","http://localhost:8080/doAjaxUpdate?id=101&name=book&remark=aaa",true);
        xhr.send(null);
    }

</script>
</body>
</html>